Three phase induction motors have a very simple construction composed of a Induction Motor stator covered with electromagnets, and a rotor made up of conductors shorted at each end, arranged as a “squirrel cage”. They work on the principle of induction where a rotating electro-magnetic field it developed by applying a three-stage current at the stators electromagnets. This in turn induces a current in the rotor’s conductors, which in turns creates rotor’s magnetic field that attempts to follow stator’s magnetic field, pulling the rotor into rotation.

Benefits of AC Induction Motors are:

Induction motors are simple and rugged in structure. They are better quality and can operate in any environmental condition

Induction motors are cheaper in cost due to simple rotor construction, lack of brushes, commutators, and slip rings

They are maintenance free motors unlike dc motors because of the absence of brushes, commutators and slip rings

Induction motors can be operated in polluted and explosive conditions as they do not have brushes that may cause sparks

AC Induction motors are Asynchronous Devices and therefore the rotor will not change at the exact same speed because the stator’s rotating magnetic field. Some difference in the rotor and stator quickness is necessary in order to produce the induction in to the rotor. The difference between your two is named the slip. Slip must be kept in a optimal range in order for the motor to operate effectively. Roboteq AC Induction controllers can be configured to operate in one of three modes:

Scallar (or Volts per Hertz): an Open up loop mode where a control causes a simultaneous, fixed-ratio Frequency and Voltage alter.

Controlled Slip: a Shut Loop speed where voltage and frequency are controlled to keep slip within a narrow range while running at a preferred speed.

Field Oriented Control (Vector Drive): a Closed Loop Speed and Torque control that works by optimizing the rotating field of the stator vs. this of the induced field in the rotor.

Discover this video from Learning Engineering for a visual illustration on how AC Induction Motors are constructed and function.